Process of preparing phthalocyanine and heterocyclic analogues



United States Patent M 3,509,146 PROCESS OF PREPARING PHTHALOCYANINE ANDHETEROCYCLIC ANALOGUES Lester Weinberger, Peufield, Paul J, Brach,Rochester, and Steven J. Grammatica, Webster, N.Y., asslgnors to XeroxCorporation, Rochester, N.Y., a corporation of New York No Drawing.Filed July 3, 1967, Ser. No. 650,589 Int. Cl. C09b 47/06 U.S. Cl.260-250 8 Claims ABSTRACT OF THE DISCLOSURE A process for thepreparation of an organic pigment which comprises mixing under reactionconditions a reactant consisting of a 1,3-diimino-isoindoline(substituted or unsubstituted) or a heterocyclic analogue of1,3-diimino-isoindoline and an alkylalkanolamine.

BACKGROUND OF THE INVENTION This invention relates in general to aprocess for the preparation of organic pigments and, more specifically,to a process for the preparation of phthalocyanine and heterocyclicanalogues of phthalocyanine.

There have been known various methods for the production of images, suchas photography, offset, xerography, and the like. In Xerography, asdisclosed by C. F. Carlson in U.S. Patent 2,297,691, a base plate ofrelatively low electrical resistance, such as metal, paper, etc., havinga photoconductive insulating surface coated thereon, iselect-rostatically charged in the dark. The charged coating is thenexposed to a light image. The charges leak ofi rapidly to the base platein proportion to the intensity of light to which any given area isexposed. The charges are substantially retained in the non-exposedareas. After such exposure the coating is contacted with electrostaticsolid marking particles in the dark. These particles adhere to the areaswhere the electrostatic charges remain, forming a powder imagecorresponding to the electrostatic image. This method is furtherdisclosed in U.S. Patents 2,659,670, 2,753,308, and 2,788,288. Thepowder image can be transferred to a sheet of transfer material,resulting in a positive or negative print as the case may be.Alternatively, where the base plate is relatively inexpensive, it may bedesirable to fix the powder image directly to the plate itself. A fulldescription of the xerographic process may be found in a book byDessauer and Clark, entitled, Xerogr-aphy and Related Processes (FocalPress Limited, 1965).

In xerography, there are known many photoconductive materials, some ofwhich function in a reusable system and others which functioncommercially only in a one-shot o-r disposable system. In the reusablesystem, while many photoconductors have been used or attempted, seleniumhas been the most commercially accepted material for use inelectrographic plates.

Although selenium is the most desirable photoconductor known today foruse in electrophotography, it does have some inherent disadvantages. Forexample, one disadvantage of the use of selenium is that it is not fullypanchromatic, being sensitive only to wavelengths shorter than about5,800 A.U. Secondly, electrographic plates made with selenium areexpensive to manufacture. A third drawback to the use of selenium is thedegree of difiiculty encountered when depositing this material upon asubstrate to form an electrographic plate. Finally, it is known thatvitreous selenium layers are only meta-stable and may be recrystallizedinto unsuitable crystalline forms at temperatures only slightly inexcess of those prevailing in conventional electrophotographic machines.

In U.S. Patent 2,663,636, Arthur Middleton disclosed 3,509,146 PatentedApr. 28, 1970 various methods and means whereby any photoconductiveinsulating material in an insulating resin binder can be formed into anoperable xerographic plate. In a copending application, Serial No.375,191, filed in the United States Patent Ofiice on June 15, 1964,entitled, Electrographic Element, the use of phthalocyanine in a resinbinder is disclosed as a xerographic plate. There are many advantagesspelled out in this application especially directed to the use ofphthalocyanine in a reusable xerogr-aphic system. Variousphthalocyanines are disclosed as suitable for use in a xerographicplate, as are many binders, both photoconductive and nonphotoconductive.

There has recently been developed an electrophoretic imaging systemcapable of producing color images which utilizes electricallyphotosensitive particles, typically phthalocyanine. This process isdescribed in detail in copending applications, Ser. Nos. 384,737,384,680, and 384,681, all filed July 23, 1964. In such an imagingsystem, various colored light absorbing particles are suspended in anon-conducting liquid carrier. The suspension is placed betweenelectrodes, one of which is generally conductive called the injectingelectrode and the other of which is generally insulating and called theblocking electrode. One of these electrodes is at least partiallytransparent. The suspension is subjected to a potential differencebetween the electrodes across the suspension and exposed to an imagethrough said partially transparent electrode. As these steps arecompleted, selective particle migration takes place in imageconfiguration providing a visible image at one or both of theelectrodes. An essential component of the system is the suspendedparticles which must be electrically photosensitive and which apparentlyundergo a net change in charge polarity upon exposure to activatingelectromagnetic radiation through interaction with one of theelectrodes.

In a monochromatic system, particles of a single color are used,producing a single-colored image equivalent to conventionalblack-and-white photography. In a polychromatic system, the images areproduced in natural color because mixtures of particles of two or moredifferent colors which are each sensitive to light of a specificwavelength or narrow range of wavelengths are used.

Phthalocyanine, also known as tetrabenzotetraazaporphin andtetrabenzoporphyrazine, may be said to be the condensation product offour isoindole groups. Metal-free phthalocyanine has the followinggeneral structure:

In addition to the metal-free phthalocyanine of the above structure,various metal derivatives of phthalocyanine are known in which the twohydrogen atoms in the center of the molecule are replaced by metals fromany group of the periodic table. Further, it is well known that from oneto sixteen of the peripheral hydrogen atoms in the four benzene rings ofthe phthalocyanine molecule may be replaced by halogen atoms and bynumerous organic and inorganic groups.

In the preparation of organic photoconductive pigments, such asmetal-free phthalocyanine, for xerographic and other electrostaticpurposes, many ditficulties have been encountered. The use of metal-freephthalocyanine in electrostatic applications places stringentrequirements on the purity of this material. For'example, it is requiredthat the phthalocyanine intendedjtor use in a xerographic plategenerally be free of impurities or contaminantswhich in one way oranother interfere with the xerographic system, whether it be in thecharge acceptance or charge dissipation step or other steps in theelectrographic process. Until now, phthalocyanine has been preparedalmost exclusively for use as a pigment where color, tinctorialstrength, light fastness, dispersibility, etc., are prime considerationsand purity is incidental. As a result, reported'methods of synthesis(see Phthalo'cyanine Compounds, by Moser and Thomas, RheinholdPublishing Company, pages 104-189) often introduce undesirable metallicor organic impurities which are diflicult to remove. Two general methodshave been used for the manufacture of metal-free phthalocyanine: (1)indirectly from an acid and a metal phthalocyanine containing areplaceable metal and (2) directly from phthalonitrile.

Methods that include forming a' metal phthalocyanine with a replaceablemetal which is subsequently removed with an acid are: heatingphthalonitrile with a sodium alcoholate (U.S. Patent 2,116,602; BritishPatent 410,814; US. Patent 2,699,441), heating phthalonitrile withsodium cyanamide (U.S. Patent 2,154,912), heating phthalonitrile withsodium cyanamide and a solvent (U.S. Patent 2,182,763; British Patent462,239), heating phthalonitrile with calcium metal in an alcohol orwith calcium or barium oxides (U.S. Patent 2,202,632), heatingphthalonitrile with calcium oxide and methylglucamine (U.S. Patent2,413,191), heating phthalonitrile with an alcohol and sodium hydride(Swiss Patent 297,412; German Patent 297,412; German Patent 933,047),heating phthalonitrile with magnesium and a solvent under pressure(British Patent 466,042; British Patent 482,387). Other methods formaking labile metal phthalocyanines include those of Linsteads andThorpes early patents (U.S. Patent 2,000,051; U.S. Patent 2,000,052;British Patent 389,842) using cyano-benzamide or phthalamidie as thephthalo- 'cyanine forming intermediate and magnesium metal. A magnesiumphthalocyanine is apparently formed by the action of a Grignard reagentsuch as methyl magnesium iodide with phthalonitrile (British Patent466,042; British Patent 480,249). Tin phthalocyanine may be prepared bya urea phthalic anhydride solvent process, but without ammonium chloride(U.S.. Patent 2,197,459).

The above-mentioned methods of synthesis generally introduce metalswhich are ditticult to remove. Methods of removing metal from labilephthalocyanines include: placing a solution of tin phthalocyanine inconcentrated sulfuric acid, followed by drowning in water (U.S. Patent2,197,459), boiling an alkali or alkali earth metal phthalocyanine withhydrochloric acid (U.S. Patent 2,216,761,), or stirring an alkali metalphthalocyanine with cold methyl alcohol, diluting with warm water, andfiltering (U.S. Patent 2,214,454). Heating an alkali metalphthalocyanine with the ammonium salt of a strong acid converts it tobeta phthalocyanine (U.S. Patent 2,686,184).

- One general method of preparing phthalocyanine which may avoidsubstantial metallic contaminants is to heat phthalonitrile to 350-360C. for 7 hours in a sealed vessel (U.S. Patent 2,116,602; British Patent410,814; US. Patent 2,153,620). A second method of synthesis which mayavoid substantial metallic contaminants is to heat phthalonitrile indimethylaniline or invquinoline solution While passing gaseousammoniarthroughthe solution; temperatures are maintained in the vicinityof 250 C. (U.S. Patent 2,116,602; British Patent 410,814; US. Patent2,153 ,620)..A third method of synthesis which'may avoid substantialmetallic contaminants is to heat phthalonitrile with acetamideand/or-formamide to the boil for 8 hours (U.S..Patent- 2,182,763;British Patent 462,239; US. Patent 2,212,924; British Patent 457,526). Afourth method is to heat phthalonitrile with dihy r xybenzene. g yco orglycerin (British Patent'466,042)'. A fifth method consists of heatingphthalonitrilein an inert solvent in the presence of cyclohexylamine orpiperidine (U.S. Patent 2,485,167). A sixth method is to heatphthalonitrile in a solvent With potassium carbonate, piperidine, andethylene glycol (U.S. Patent 2,485,167; US. Patent 2,485,168). Finally,a seventh method of synthesis of phthalocyanine which may avoidsubstantial metallic contaminants is to add. a catalytic amount oftriethanolamine to molten phthalonitrile at temperatures of 170 to 180C.(U.S. Patent 2,155,054).

While the above seven methods of phthalocyanine synthesis avoid theintroduction of inetal impurities, side reactions occur with a resultinglower yield of pigment due to the high temperatures at which thesemethods of synthesis are carried out. In addition, complex organicimpurities are introduced. These organic impurities are difficult toremove and cannot be tolerated in the phthalocyanine compound when it isto'be used for electrostatic purposes. It is, therefore, an object ofthis invention to provide a method for the preparation of asubstantially pure organic pigment devoid of the above-noteddisadvantages.

It is, another object of this invention to provide a direct method forthe preparation of an organic pigment without the use of metals ormetallic salts, whereby substantially all contaminants in the finalproduct are avoided.

It is still another object of this invention to provide a direct methodfor the preparation of a substantially pure organic pigment wherein theyield of the resulting product is significantly high.

It is still another object of thisinvention to provide a direct methodfor the preparation of a substantially pure organic pigment Which takesplace under mild reaction conditions.

It is yet another object of this invention to provide a direct methodfor the preparation of a substantially pure organic pigment wherein thefinal product has excellent properties for use in an electrostaticimaging system.

It is still another object of this invention to provide a method for thepreparation of an organic pigment in which there is ease of isolationand purification of the resulting product.

It is still another further object of this invention to provide alow-cost method for the preparation of substantially pure organicpigment.

SUMMARY OF THE INVENTION The foregoing objectives, and others, areaccomplished in accordance with this invention, generally speaking, byproviding a novel system for the preparation of a highly pure organicphotoconductive pigment which comprises mixing under reaction conditionsan alkylalkanolamine and a 1,3-diimino-isoindoline or a heterocyclicanalogue of 1,3-diimino-isoindoline.

Any suitable ratio of 1,3-dimino-isonodoline or heterocyclic analogue of1,3-diimino-isoindo1ine to alkylalkanolamine may be employed in thisprocess. However, best yields of the desired resulting products areobtained when this ratio is from approximately 1:5 parts, by weight, toapproximately 1:10 parts, by Weight. Best yields are obtained byemploying a ratio of approximately 1 part, by weight, of1,3-diimin0-is0indoline or 1 part, by weight, of a heterocyclic analogueof 1,3-diimino-isoindoline to approximately 5'parts, by weight, ofalkylalkanolaminc;

Although the reaction may becarried out at any suitable temperature, therange of about C. to about 280 C. has been found convenient. While anyappropriate temperature may be used depending upon the com.- ponentsselected for this system, it is preferred that a temperature generallyin the. range of about 100 C. to about C. be used because at thistemperature it is found that fewer'side reactions occur and a purerprodduct is obtained.

Any suitable alkylalkanolamine may be used in this system. Typicalalkylalkanolamines are Z-dimethylaminoethanol,1-dimethylamino-Z-propanol, 1-diethylamino-2-propanol,Z-dimethylamino-Z-methyl-l-propanol, 2-diethylaminoethanol,3-dimethylamino-l-propanol, 2-(di-iso-propylamino) ethanol,Z-butylaminoethanol, Z-dibutylaminoethanol, 2[(2-(diethylamino) ethyl)amino]ethanol 2,2'-(butylimino) diethanol, Z-ethylaminoethanol,

2,2'-(ethylimino) diethanol, Z-methylaminoethanol, 2,2'-(methylimino)diethanol, 2-(iso-propylamino) ethanol, 2,2'-(isopropylimino) diethanol,2,2'-(tert.-butylimino) diethanol, and 3-diethylamino-l-propanol, amongothers.

Although any suitable alkylalkanolamine may be used in this system, itis preferred that Z-dimethylaminoethanol (reflux temperature, about 131C. to 135 C.), l-dimethylamino-2-propanol (reflux temperature, about 126C.- 127 C.), or 1-diethylamino-2-propanol (reflux temperature, about 153C.-160 C.) be used because higher yields of substantially pure organicpigment are obtained. Optimum results are obtained with2-dimethylaminoethanol.

Although any suitable 1,3-diimino-isoindoline or substituted orunsubstituted heterocyclic analogue of 1,3-diimino-isoindoline may beused in this system, it is preferred that unsubstituted1,3-diimino-isoindoline,

5 -nitro-1 3-diimino-isoindoline, S-acetamido-l,3-diimino-isoindoline,

4,5 ,6,7-tetrachloro-l ,3-diimino-isoindoline, 4,5,6,7-tetrabromo-1,3-diimino-isoindoline, 5 -chloro-1,3-diimino-isoindoline,

the unsubstituted or halogen, CF S N0 CN, NH;, CH C H C3H7, or C Hsubstituted pyrazino analogue of 1,3-diimino-isoindoline, unsubstitutedor halogen, CF S0 N0 CN, NH CH C H C3H7 or C H substituted1,3-diimino-4,7-dithia-4,5,6,7-tetrahydro-isoindoline, the unsubstitutedor halogen, CF S0 N0 CN, NH CH C H C H or C H substituted quinalineanalogue of 1,3-diimino-isoindoline, orthe unsubstituted or halogen,CF13, S03, N02, CN, NHg, CH3, C2H5, C3H7 01' C4H9 substituted pyridineanalogue of 1,3-diimino-isoindoline be used to obtain organic pigmentsof high photoconductivity.

While any suitable 1,3-diimino-isoindoline may be used in this process,it is most preferred that unsubstituted 1,3- diimino-isoindoline beemployed in order that an end product with substantially greaterphotoconductivity and panchromaticity, namely metal-free phthalocyanine,be obtained. While any suitable analogue of 1,3-diiminoisoindoline maybe used in this system, it is most preferred that the unsubstitutedpyrazino analogue be employed in Order to obtain a. substantially pureorganic pigment of excellent photoconductivity.

DESCRIPTION OF PREFERRED EMBODIMENTS The following examples will furtherdefine various preferred embodiments of the present invention. Parts andpercentages are by weight unless Otherwise specified.

Example I About 1 part, by weight, of 1,3-diimino-isoindoline and about5 parts, by weight, of 2-dimethylaminoethanol are placed in a flaskequipped with a mechanical stirrer and thermometer. The suspension isstirred and heated to reflux (about 131 C. to about 135 C.). Thistemperature is maintained for approximately 10 minutes during which timeNH is given 01?. The above mixture is then filtered hot and the residueis washed thoroughly, first with water and then with acetone. Finally,the residue is air-dried. The resulting product consists of very purebeta metalfree phthalocyanine. Exhaustive extraction with hotdimethylformamide and isopropanol show the presence of less than 0.1%liquid and solid impurities. The yield of the said product is about ofthe theoretical yield.

Example II About 1 part, by weight, of 1,3-diimino-isoindoline and about12 parts, by weight, of Z-dimethylaminoethanol are placed in a flaskequipped with a mechanical stirrer and thermometer. The suspension isstirred and heated to reflux (about 131 C. to about 135 C.). Thistemperature is maintained for approximately 25 minutes during which timeNH is given off. The above mixture is then filtered hot and the residueis washed thoroughly, first with acetone and then with methanol andwater. Finally, the residue is dried in a vacuum for approximately 6hours at approximately 55 C. The resulting product consists of very purebeta metal-free phthalocyanine. Exhaustive ex traction with hotdimethylformamide and isopropanol show the presence of less than 0.1%liquid and solid impurities. The yield of said product is about 85% ofthe theoretic yield.

Example III About 1 part, by weight, of 1,3-diimino-isoindoline andabout '8 parts, by weight, of 1-dimethylamino-Z-propanol are placed in aflask equipped with a mechanical stirrer and thermometer. The suspensionis stirred and heated to reflux (about 126 C. to about 127 C.). Thistemperature is maintained for approximately 30 minutes during which timeNH is given otf. The above mixture is then filtered and the residue iswashed thoroughly, first with water and then with ethanol. Finally, theresidue is air-dried. The resulting product consists of very pure betametal-free phthalocyanine. Exhaustive extraction with hotdimethylformamide and isopropanol show the presence of less than 0.1%liquid and solid impurities. The yield of said product is about 85% ofthe theoretical yield.

Example IV About 1 part, by weight, of S-nitro-1,3-diimino-isoindolineand approximately 6 parts, by weight, of l-diethylamino-Z-propanol areplaced in a flask equipped with a mechanical stirrer and thermometer.The suspension is stirred and heated to reflux (about 153 C. to aboutC.). This temperature is maintained for approximately 5 hours duringwhich time NH is given off. The above mixture is then filtered hot andthe residue is washed thoroughly, first with water and then with acetoneand ethanol. Finally, the residue is air-dried. The resulting productconsists of very pure tetra (4) nitro-phthalocyanine. Exhaustiveextraction with hot dimethylformamide and isopropanol show the presenceof less than 0.1% liquid and solid impurities. The yield of said productis about 85% of the theoretical yield.

Example V About 1 part, by weight, of 5-acetamido-1,3-diiminoisoindolineand about 9 parts, by weight, of Z-dirnethylamino-Z-methyl-l-propanolare placed in a flask equipped with a mechanical stirrer andthermometer. The suspension is stirred and heated to reflux (about 159C. to about 161 C.). This temperature is maintained for approximately 6hours during which time NH is given off. The above mixture is thenfiltered hot and the residue is washed thoroughly, first with acetoneand then with water. Finally, the residue is dried in a vacuum forapproximately 5 hours at about 60 C. The resulting product consists ofvery pure tetra (4) acetamidophthalocyanine. Exhaustive extraction withhot dimethylformamide and isopropanol show the presence of less than0.1% liquid and solid impurities. The yield of said product is about 80%of the theoretical yield.

Example VI About 1 part, by weight, of4,5,6,7-tetrachloro-l,3-diirnino-isoindoline and about parts, by Weight,of 2- diethylaminoethanol are placed in a flask equipped with amechanical stirrer and thermometer. The suspension is stirred and heatedto reflux (about 161 C. to about 163 C.). This temperature is maintainedfor approximately 4 hours during which time NH is given ofi. The abovemixture is then filtered and the residue is washed thoroughly, firstwith ethanol and then with acetone. Finally, the residue is air-dried.The resulting product consists of very purehexadecachlorophthalocyanine. Exhaustive extraction with hotdimethylformamide and isopropanol show the presence of less than 0.1%liquid and solid impurities. The yield of said product approaches 80% ofthe theoretical yield,

Example VII About 1 part, by weight, of4,S,6,7-tetrabromo-1,3-diimino-isoindoline and about parts, by weight,of 3-dimethylamino-l-propanol are placed in a flask equipped with amechanical stirrer and thermometer. The suspension is stirred and heatedto reflux (about 165 C. to about 167 C.). This temperature is maintainedfor approximately 6 hours during which time NH is given off. The abovemixture is then filtered hot and the residue is washed thoroughly, firstwith acetone and then with water and ethanol. Finally, the residue isair-dried. The resulting product consists of very purehexadecabromophthalocyanine. Exhaustive extraction with hotdimethylformamide and isopropanol show the presence of less than 0.1%liquid and solid impurities. The yield of said product is about 80% ofthe theoretical yield.

Example VIII About 1 part, by weight, of 5-chloro-1,3-diiminoisoindolineand about 7 parts, by weight, of Z-(di-isopropylamino) ethanol areplaced in a flask equipped with a mechanical stirrer and thermometer.The suspension is stirred and heated to reflux (about 191 C. to about193 C.). This temperature is maintained for approximately 5 hours duringwhich time NH is given ofi. The about mixture is then filtered hot andthe residue is washed thoroughly, first with water and then withacetone. Finally, the residue is dried in a vacuum for approximately 7hours at about 50 C. The resulting product consists of very pure tetra(4) chlorophthalocyanine. Exhaustive extraction with hotdimethylformamide and isopropanol show the presence of less than 0.1%liquid and solid impurities. The yield of said product is about 80% ofthe theoretical yield.

Example IX About 1 part, by weight, of the pyrazino analogue of1,3-diimino-isoindoline, having the structure:

ifiIH N it is dried in a vacuum for approximately 7 hours at about 50 C.The resulting product consists of an organic pigment having thestructure:

NH HN A N C C .a/ at N N Ly Exhaustive extraction with hotdimethylformamide and isopropanol show the presence of less than 0.1%liquid and solid impurities. The yield of said product is about of thetheoretical yield.

Example X About 1 part, by weight, of chlorine substituted 1,3- diimino4,7-dithia-4,5,6,7-tetrahydro-isoindoline, having the structure:

ethanol. Finally, it is air-dried. The resulting product consists of anorganic pigment having the structure:

Exhaustive extraction with hot dimethylformamide and isopropanol showthe presence of less than 0.1% liquid and solid impurities. The yield ofsaid product is about 80% of the theoretical yield.

Example XI Aboutl part, by weight, of the methyl substituted quinalineanalogue of 1,3-diimino-isoindolin, having the structure:

s ur on and approximately 8 parts, by weight, of 2[(Z-diethylamino)]ethanol are placed in a flask equipped with amechanical stirrer and thermometer. The suspension is stirred and heatedto reflux (about 240 C. to about 243 C.). This temperature is maintainedfor approxi mately 1 hour during which time NH is given 01f. The abovemixture is then filtered, and the residue is washed thoroughly, firstwith water and then with acetone. Finally, it is dried in a vacuum forapproximately 6 hours at about 55 C. The resulting product consists ofan organic pigment having the structure:

Exhaustive extraction with hot dimethylformamide and isopropanol showthe presence of less than 0.1% liquid and solid impurities. The yield ofsaid product is about 75% of the theoretical yield.

Example XII About 1 part, by weight, of the pyridine analogue of1,3-diimino-isoindoline, having the structure:

and about 6 parts, by weight, of 2-diethylaminoethanol are placed in aflask equipped with a mechanical stirrer and thermometer. The suspensionis stirred and heated to reflux (about 161 C. to about 163 C.). Thetemperature is maintained for approximately 1 /2 hours during which timeNH is given ofl. The above mixture is filtered hot, and the residue iswashed, first with water and then with methanol. Finally, it isair-dried. The resulting product consists of an organic pigment havingthe structure:

Exhaustive extraction with hot dimethylformamide and isopropanol showthe presence of less than 0.1% liquid and solid impurities. The yield ofsaid product is about 80% of the theoretical yield.

While specific components of the present system are defined in theworking examples above, any of the other typical materials indicatedabove, if suitable, may be substituted in the working examples. Inaddition, many other variables may be introduced in the present processsuch as further purification steps or other reaction compOnents whichmay in any way affect, enhance, or otherwise improve the presentprocess.

While various specifics are given in the present application, manymodifications and ramifications will occur to those skilled in the artupon reading of the present disclosure. These are intended to beencompassed within the scope of this invention.

What is claimed is:

1. The process for the preparation of a member selected from the groupconsisting of tetraazaporphins and where A is selected from the groupconsisting of and where R is selected from the group consisting of H, ahalogen, CF SOgH, N0 CN, NH CH C H C H and C H and where n is a positiveinteger from 1 to 2 and m is a positive integer from 1 to 3, andcombinations thereof;

(b) heating said mixture to reflux temperature; and

(c) maintaining said temperature for a period of about 10 minutes toabout 7 hours.

2. The process according to claim 1 wherein said alkylalkanolamine isselected from the group consisting of 2-dimethylaminoethanol,l-dimethylamino 2 propanol, and 1-diethylamino-2-propanol.

3. The process according to claim 1 wherein said substituted1,3-diimino-isoindoline is selected from the group consisting ofS-nitro-l, S-diimino-isoindoline, S-acetamido-l, 3-diimino-isoindoline,4,5,6,7-tetrachloro-1, 3-diimino-isoindoline, 4,5,6,7-tetrabromo 1, 3diimino-isoindoline, and S-chloro-l, 3-diimino-isoindoline.

4. The process according to claim 1 wherein the ratio of saidalkylalkanolamine to said reactant ranges from about 5:1, by weight, toabout 10:1, by weight.

5. The process according to claim 1 wherein said alkylalkanolamine isZ-dimethylaminoethanol.

6. The process according to claim 1 wherein said re- References Citedactant is unsubstituted 1,3-diimino-isoindoline. UNITED STATES PATENTS7. The process according to claim 1 wherein said re- 2,752,346 6/1956R5Sch et 1 5 actant is the unsubstituted pyrazino analogue of 1,3-dirHENRY R- ULES, Primary Examiner immoisolndoline. 0

8. The process according to claim 1 wherein the ratio MOATZ AssistantExaminer of said alkylalkanolamine to said reactant is about 5:1, US.Cl. X.-R.

y Weight 260-288, 296, 314.5

